It is axiomatic in explosives that for maximum explosion force it is necessary to pack the explosive material as tightly as possible into its container, both to maximize the amount of material and to eliminate force-deadening voids. A modified (dense) packing is particularly also important for propellant charges which must give uniform propellant force from projectile to projectile for uniform artillery results.
German patent document No. 2,504,756 describes an arrangement for use as a grenade or propellant charge. In this arrangement the particulate explosive or propellant material is filled into a bottle-like canister and then the mouth of the canister is closed by a fitting which carries an expansible bladder inside the bottle. The interior of the bladder is pressurized while the space inside the canister around the bladder is pumped out, causing the bladder to swell and press against the unpacked mass of explosive or propellant in the canister, exerting enough pressure to pack it tightly therein. After a few such filling and compacting operations the interior of the canister is tightly packed.
This method is relatively cumbersome with its several steps. In addition the charge ends up being packed in stratified layers, as with each packing operation the uppermost layer is packed with a density gradient that increases upward. The explosion of such a stratified charge is nonuniform, and in fact thorough explosion may not take place. The desired explosion of a charge from the center out is not obtained with such an axially stratified charge.